Metal composite hydroxide and method for producing the same, positive electrode active material for lithium ion secondary battery and method for producing the same, and lithium ion secondary battery using the same

Abstract

A method for producing a metal composite hydroxide, which includes a first crystallization process of supplying a first raw material aqueous and performing a crystallization reaction and a second crystallization process of supplying a second raw material aqueous solution containing a more amount of tungsten than the first raw material aqueous solution and performing a crystallization reaction to form a tungsten-concentrated layer and in which switching of reaction atmosphere from either atmosphere of a non-oxidizing atmosphere or an oxidizing atmosphere to the other atmosphere is performed two or more times in particle growth and the time for supplying the second raw material aqueous solution into the reaction tank in the non-oxidizing atmosphere is 50% or more with respect to the entire time for supplying the second raw material aqueous solution into the reaction tank.

The invention claimed is: 
     
         1 . A metal composite hydroxide that contains nickel, manganese, and tungsten and optionally cobalt and element M and has a mass ratio of the respective metal elements represented by Ni:Mn:Co:W:M=x:y:z:a:b (x+y+z=1, 0.3≤x≤0.95, 0.05≤y≤0.55, 0≤z≤0.4, 0<a≤0.1, 0≤b≤0.1, and M is one or more elements selected from the group consisting of Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, Hf, and Ta), the metal composite hydroxide comprising:
 secondary particles with a plurality of aggregated primary particles, wherein 
 the secondary particles have a multilayer structure including a center at which the primary particles are densely disposed, a void at which the primary particles are more sparsely disposed than the center, and a solid portion which corresponds to a surface portion of the secondary particles at which the primary particles are densely disposed from a center of the secondary particles toward a surface, 
 a tap density is 0.75 g/cm 3  or more and 1.35 g/cm 3  or less, 
 a tungsten-concentrated layer is formed at a surface part of the solid portion such that tungsten is contained in the surface part of the solid portion at a higher concentration than in the void and the center in the secondary particles, 
 an average particle size of the composite hydroxide is 4.0 μm or more and 9.0 μm or less, and 
 a thickness of the tungsten-concentrated layer is 100 nm or less. 
 
     
     
         2 . The metal composite hydroxide according to  claim 1 , wherein a thickness of the tungsten-concentrated layer is 35 nm or more and 100 nm or less. 
     
     
         3 . The metal composite hydroxide according to  claim 1 , wherein [(d90−d10)/average particle size] that is an index indicating spread of particle size distribution is 0.65 or less.